Well, this is fun. Just in case you felt that GTA V doesn't have enough GTA, this is a GTA V mod which puts more GTA 2 into your GTA V.
That's a lot of GTA.
Mods which add features from a previous installment of a franchise into a newer release are hardly a new concept... even within the realm of GTA V, with mods bringing over the maps of previous GTA games into the engine of the newest blockbuster in the series.
Considering the number of games in the GTA franchise, it is clear that the various games won't have the same features, and while as time progressed, more and more features were added, some old mission types and game modes have also been cut, regardless of their popularity at the time.